DEVELOPMENT OF A NEW METHOD FOR THE ANALYSIS OF COSMETIC AND PHARMACEUTICAL TALC FOR ASBESTOS

The analysis of cosmetic and pharmaceutical talc for asbestos has recently become a global topic, with products of questionable quality reportedly found in Korea and China; also prompting testing by the US FDA of products marketed in the United States. Different origins of talc deposits produce major differences in type and purity of talc ore. Differences between pharmaceutical and industrial grade talc are discussed and compared with historical references to these terms.

Existing methods developed for the analysis of construction materials for asbestos are inadequate for the analysis of talc ore and products. Other methods, developed specifically to help talc raw material suppliers comply with voluntary quality standards, include those developed by the USP (United States Pharmacopeia) and PCPC (Personal Care Product Council) trade association – formerly CTFA (Cosmetics, Toiletries, and Fragrance Association). These methods need to be further developed in order to fully enhance their effectiveness.

The American Society of Testing and Materials (ASTM) has proposed development of a new method that will incorporate existing procedures and close the gaps present in existing methods. ASTM is working with USP to develop a multidisciplinary approach using X-ray diffraction (XRD), polarized light microscopy (PLM), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Analysis of the largest size fraction in talc products is shown to enhance detection of asbestos in talc for all methods. This facilitates the use of PLM, the quickest and least expensive of all the techniques. Initial results show that tremolite asbestos can be detected in a milled talc product by PLM when other methods indicate the content is on the order of 100 ppm. Therefore, it appears that a quick and reliable method by PLM can be developed for ppm-level asbestos analysis in talc products.

As a previous student of Don Bloss, I am deeply indebted to him for his kind and patient introduction into the world of optical microscopy. Without his painstakingly crafted illustrations presented through his classes and in his textbooks, this topic may well have been out of reach for many students.